Drill



u y-2 1 3 w. I. CHURCH 12,088 012! DRILL Filed Nov. 19, 1954 aw J 2.

1 1 Walter 'L Church, HouStonQ'Tex Atsiiaem mim 19,'1934, Serial No. 753,675

3 zfclaims. ((1255-51) I v M I the externally threaded pint of the tool joint member'lis threaded. This tool joint member .1 I

This invention relates to apparatus and method forfdrilling wells.

The invention relates primarily to drilling throughformations having a tendency to cave,

and' particularly to that type of formation commonly known as heaving shale. In drilling a well through .heaving. shale formation, the formation is liable to cave in against the drill stem so that the same can not be rotated orwithdrawn; and if the drill stem is once withdrawn, the formation is liable to cavein andcompletely destroy the bore so that a new bore must be formed often'with like results. It isthe primary object of this invention to provide a novel of apparatus whereby the method hereinafter described may be employed to advance thebore in stages through the caving formation an'dinto the stratum beneath. v With the above and other objects in view, the invention has particular relation to certain novel features of construction, and use, and example of which is given in this specification and illustrated in the accompanying drawing, wherein:-

Figure 1 shows aside elevation partly in section showing the surfacecasing, as set in the well and illustrating the upper section of casing to be set in the caving formation, with the drill attached to the lower end thereof. Figure 2 shows a side view partly in section of the upper section of casing to be set in thecaving formation, illustrating also, a reduced section of the casing advanced further into the formation. g

Figure. *3 shows a sideview partly in section of a complete string of easing reduced from above downwardly as assembled in a well which has been completed through the formation.

Figure 4 shows a cross-sectional view taken on the line 4-4 of Figure 1, and I Figure 5 shows a fragmentary side elevation partly in section, illustratingthe relation of the upperend of the string of casing setin' the caving formation, with the surface casing show'ing also the packing between them.

Referring now more particularlyto the drawstring of casing, as l8, with a drillfl la, in all ing whereinlike numerals of reference designate similar parts in each of the figures, the numeral I designates a surface casing whose lower end at any required depth, but above the caving formation to be'encountered. Beneath the surface casing 'l, thereis' a string of casing 3 whose upper end is equipped with a coupling 4 having an internal coarsely threaded'box 5,.into which is connected tothe lower end of the drill stem 8. It is reducedbeneath its upperend forming the external annular shoulder 9 which is spaced above 5 x the upper end of thecoupling 4 and between I said upper end, and the shoulder 9, there is a ring l0 which is keyedon the pin 6 so as to be rotatableindependently thereof. The upper andlower, margins of the ring I 0 have the reversely pitched 10 ratchet teeth I I, I2, provided to engage the shoulder 8 and the upper end of the coupling 4 respectively, so that the pin 6 will not be screwed too tightly into the box .5, to the end that the joint may be readily unscrewed and separated. 1E The thre'ads'connecting the pin and box are protected by means of the packing ring l3 around the lower end of said pin so that the gritty drillingfluid under pressure will not cut out the threads, but may act, throughcthe ports 6a, to

expand the packing.

Attached to the lower end of the string of cas-,. ing 3 there is a drill l4 formed with a hollow. head and radial blades l5. Thelower ends of the blades are separated from the upper portions thereof by the slots lfi'extending from the outer margins of the blades to the head, as shown in Figure 1. The head of the drill is provided with suitable outlet openings l1 for the outlet of the drilling fluid which is forced underpressure down the left to unscrewthe pin Q from the box 5 and 4 the drill stem is then withdrawn from the well.

' A milling toolis then lowered. into the well and the lower end of the drill I4 is milled out and the sections of the blades l5 beneath the slots l5 7 will drop off and may be side-tracked. A smaller respects similar to the drill I4, is then lowered into the well and through the casing 3 and drilling is proceeded with. This smaller casing I8 is connected to the drill stem 8, as hereinabove ex- 'plained, and the bore is deepened through the heaving shale formation with the casing l8 as far as possible. When drilling can not becarrled on further, the drill stem is again detached from the string l3,-'as before and a drilling tool is lowered to drill off the lower end of the drill Ma as hereinabove explained. A still smaller string of easing, as I9 is then lowered into the well as before through the strings 3 and I8, and the bore is further deepened. This string I9 has the drill Mb on the lower end thereof similar to the drill l4 and the method may thus be prooeeded with until the bore has passed beneath the heaving shale stratum. It will be noted that each string of easing, 3, l8, and I9, is left permanently in the well to hold up the caving formationand to preserve the bore. After the lower string of easing l9 has been set, its drill Mb may be milled away, as herein above explained, and the drilling operations resumed to carry the bore to the desired depth. The lower string of casing, as I9, is preferablyextended on up through the larger strings of casing above and into the surface casing I, and a packer 20 of conventional construction is then set between the upper end of the inner or smaller string 19, and

the surface casing I so as to prevent the water from any stratum that may be encountered from entering the casing I9.

The upper end of any intermediate string of easing so set should preferably extend up into the lower end of, the string next above, as illustrated in Figure 3.

When the heaving shale has been cased off,

as hereinabove explained, the well may then be completed and brought in without any interference from the caving formation.

What I claim is:--

1. A drill for use in drilling wells comprising a thin walled, closed, hollow head, blades on its lower end, said blades being formed of two portions separated by a narrow slot which extends from the head to the outer margins of the blades whereby the lower portion of the head and blades may be removed from the remainder of the drill by milling through the wall of the head at a point in line with the slots in the'blades, the lower portion of the blades having cutting edges extending substantially to the longitudinal axis of the drill.

2. A drill for use in drilling wells comprising a thin walled, ,closed, hollow head, blades on its lower end, said blades being formed of portions separated by'a narrow slot which extend from the head to the outer margins of the corresponding blades whereby the lowerportion of the head and blades may be removed from the remainder of the drill by milling through the wall of the head at a point in line with the inner ends of the slots in the blades, thelower portions of the blades having cutting edges extending substantially to the longitudinal axis of the drill.

- WALTER L. CHURCH. 

